Sounds like you got a faulty replacement from the supplier, or the dealer is damaging the replacement sensor during the installation. It is critical that the windshield surface where the sensor mounts is clean. If they left residue or debris from the previous failed sensor, the new sensor may have been damaged upon installation.
Not sure why they claimed a road test for calibration; no calibration procedure is necessary for a rain sensor. Makes you wonder if they even read the WSM.